import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;

public class MapTest {
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<String, String>();
        map.put("20175212", "thz");

        Iterator<String> iterator = map.keySet().iterator();
        while (iterator.hasNext()) {
            Object key = iterator.next();
            System.out.println("map.get(" + key + ") is :" + map.get(key));
        }
        System.out.println("-------------------");

        Hashtable<String, String> tab = new Hashtable<String, String>();
        tab.put("20175212", "thz");

        Iterator<String> iterator_1 = tab.keySet().iterator();
        while (iterator_1.hasNext()) {
            Object key = iterator_1.next();
            System.out.println("tab.get(" + key + ") is :" + tab.get(key));
        }
        System.out.println("-------------------");

        TreeMap<String, String> tmp = new TreeMap<String, String>();
        tmp.put("20175212", "thz");

        Iterator<String> iterator_2 = tmp.keySet().iterator();
        while (iterator_2.hasNext()) {
            Object key = iterator_2.next();
            System.out.println("tmp.get(" + key + ") is :" + tmp.get(key));
        }
    }
}